content: /**
   * Copyright (c) 2016-present, RxJava Contributors.
   *
   * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in
   * compliance with the License. You may obtain a copy of the License at
   *
   * http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software distributed under the License is
   * distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See
   * the License for the specific language governing permissions and limitations under the License.
   */
  
  package io.reactivex.flowable.internal.operators;
  
  import java.util.concurrent.atomic.*;
  
  import org.reactivestreams.*;
  
  import hu.akarnokd.reactivestreams.extensions.RelaxedSubscriber;
  import io.reactivex.common.exceptions.MissingBackpressureException;
  import io.reactivex.flowable.Flowable;
  import io.reactivex.flowable.internal.subscriptions.SubscriptionHelper;
  import io.reactivex.flowable.internal.utils.BackpressureHelper;
  import io.reactivex.flowable.subscribers.SerializedSubscriber;
  
  public final class FlowableSamplePublisher<T> extends Flowable<T> {
      final Publisher<T> source;
      final Publisher<?> other;
  
      final boolean emitLast;
  
      public FlowableSamplePublisher(Publisher<T> source, Publisher<?> other, boolean emitLast) {
          this.source = source;
          this.other = other;
          this.emitLast = emitLast;
      }
  
      @Override
      protected void subscribeActual(Subscriber<? super T> s) {
          SerializedSubscriber<T> serial = new SerializedSubscriber<T>(s);
          if (emitLast) {
              source.subscribe(new SampleMainEmitLast<T>(serial, other));
          } else {
              source.subscribe(new SampleMainNoLast<T>(serial, other));
          }
      }
  
      abstract static class SamplePublisherSubscriber<T> extends AtomicReference<T> implements RelaxedSubscriber<T>, Subscription {
  
          private static final long serialVersionUID = -3517602651313910099L;
  
          final Subscriber<? super T> actual;
          final Publisher<?> sampler;
  
          final AtomicLong requested = new AtomicLong();
  
          final AtomicReference<Subscription> other = new AtomicReference<Subscription>();
  
          Subscription s;
  
          SamplePublisherSubscriber(Subscriber<? super T> actual, Publisher<?> other) {
              this.actual = actual;
              this.sampler = other;
          }
  
          @Override
          public void onSubscribe(Subscription s) {
              if (SubscriptionHelper.validate(this.s, s)) {
                  this.s = s;
                  actual.onSubscribe(this);
                  if (other.get() == null) {
                      sampler.subscribe(new SamplerSubscriber<T>(this));
                      s.request(Long.MAX_VALUE);
                  }
              }
  
          }
  
          @Override
          public void onNext(T t) {
              lazySet(t);
          }
  
          @Override
          public void onError(Throwable t) {
              SubscriptionHelper.cancel(other);
              actual.onError(t);
          }
  
          @Override
          public void onComplete() {
              SubscriptionHelper.cancel(other);
              completeMain();
          }
  
          boolean setOther(Subscription o) {
              return SubscriptionHelper.setOnce(other, o);
          }
  
          @Override
          public void request(long n) {
              if (SubscriptionHelper.validate(n)) {
                  BackpressureHelper.add(requested, n);
              }
          }
  
          @Override
          public void cancel() {
              SubscriptionHelper.cancel(other);
              s.cancel();
          }
  
          public void error(Throwable e) {
              s.cancel();
              actual.onError(e);
          }
  
          public void complete() {
              s.cancel();
              completeOther();
          }
  
          void emit() {
              T value = getAndSet(null);
              if (value != null) {
                  long r = requested.get();
                  if (r != 0L) {
                      actual.onNext(value);
                      BackpressureHelper.produced(requested, 1);
                  } else {
                      cancel();
                      actual.onError(new MissingBackpressureException("Couldn't emit value due to lack of requests!"));
                  }
              }
          }
  
          abstract void completeMain();
  
          abstract void completeOther();
  
          abstract void run();
      }
  
      static final class SamplerSubscriber<T> implements RelaxedSubscriber<Object> {
          final SamplePublisherSubscriber<T> parent;
          SamplerSubscriber(SamplePublisherSubscriber<T> parent) {
              this.parent = parent;
  
          }
  
          @Override
          public void onSubscribe(Subscription s) {
              if (parent.setOther(s)) {
                  s.request(Long.MAX_VALUE);
              }
          }
  
          @Override
          public void onNext(Object t) {
              parent.run();
          }
  
          @Override
          public void onError(Throwable t) {
              parent.error(t);
          }
  
          @Override
          public void onComplete() {
              parent.complete();
          }
      }
  
      static final class SampleMainNoLast<T> extends SamplePublisherSubscriber<T> {
  
          private static final long serialVersionUID = -3029755663834015785L;
  
          SampleMainNoLast(Subscriber<? super T> actual, Publisher<?> other) {
              super(actual, other);
          }
  
          @Override
          void completeMain() {
              actual.onComplete();
          }
  
          @Override
          void completeOther() {
              actual.onComplete();
          }
  
          @Override
          void run() {
              emit();
          }
      }
  
      static final class SampleMainEmitLast<T> extends SamplePublisherSubscriber<T> {
  
          private static final long serialVersionUID = -3029755663834015785L;
  
          final AtomicInteger wip;
  
          volatile boolean done;
  
          SampleMainEmitLast(Subscriber<? super T> actual, Publisher<?> other) {
              super(actual, other);
              this.wip = new AtomicInteger();
          }
  
          @Override
          void completeMain() {
              done = true;
              if (wip.getAndIncrement() == 0) {
                  emit();
                  actual.onComplete();
              }
          }
  
          @Override
          void completeOther() {
              done = true;
              if (wip.getAndIncrement() == 0) {
                  emit();
                  actual.onComplete();
              }
          }
  
          @Override
          void run() {
              if (wip.getAndIncrement() == 0) {
                  do {
                      boolean d = done;
                      emit();
                      if (d) {
                          actual.onComplete();
                          return;
                      }
                  } while (wip.decrementAndGet() != 0);
              }
          }
      }
  }
  